CHAPTER VII 



DYNAMICS OF LUMINESCENCE 



One of the most extraordinary things regarding lumi- 

 nescence in general is the small amount of material neces- 

 sary to cause a visible emission of light. To take an ex- 

 treme case, the flash of light resulting from the impact on 

 ZnS of a single a particle, a helium atom, is visible to 

 the naked eye. Addition of one part in a million of some 

 heavy metal to pure CaS will confer phosphorescent prop- 

 erties on the latter. "We are forced to believe that the 

 heavy metal enters into some reaction during illumination 

 which is reversed with light emission after illumination 

 and a very small amount of heavy metal is necessary. 

 Pyrogallol in water, 1 : 5,000,000 (m/512,000), can be oxi- 

 dized with light production by K4Fe(CN)8 and H2O2 

 (Harvey, 1917) and m/100 pyrogallol + HjOj will give a 

 visible light with colloidal platinum in 1 : 250,000 concen- 

 tration (Goss, 1917). 



Lucif erin and lucif erase from Cypridina will also lumi- 

 aesce in exceedingly small concentration. If one grinds 

 a single Cypridina in a mortar with water and dilutes the 

 extract to 25,600 cc, light can be observed if luciferin is 

 added to this dUute luciferase solution. By determining 

 the volume of the luminous gland of Cypridina and even 

 issuming that this volume is all luciferase, one can calcu- 

 late that one part ,of luciferase in 1,700,000,000 parts of 

 prater will give light when luciferin is added. Likewise, 

 I similar dilution of luciferin will give visible light when 

 uciferase is added. 



14S 



